Oil well pump



Jan. 27, 1948. I A; C, MCGOVNEY 2,435,179

OIL WELL PUMP d ATTORNEYS.

Jan. 27, 1948.

A. C. MCGOVNEY OIL WELL' PUMP Filed March 25, 1946' 2 Sheets-Sheet 2 V7 rrr IT l lNVENTOR ALBERT CARL Me GOVNEY t( T l RNEYS.

Patented `ian.. 27, 1948 STATES AET on. WELL PUMP Albert Carl McGovney, Coffeyville, Kans., assignor to Multscope, Inc., Coieyville, Kans., a corporation of Kansas 'I'his invention relates generally to the pumping of deep wells, such as oil wells, and has particular reference to a self-contained, electrically driven pumping arrangement adapted to pump oil wells without necessitating the running of tube,

lines from the bottom of the well to the surface ofthe ground.

While the conventional method of pumping oil wells involves the provision of a pump on the surface of the ground with tubing and sucker rods extending down through the bore hole to the producing formation, numerous efforts have been made to eliminate sucker rods. Such devices as have been suggested, however, have eitherinot completely avoided the necessity of running tube lines to the surface of the ground or have been of such character that the pump was relatively short lived.

The object of the present invention, generally stated, is to provide a deep well pump adapted to be disposed near the bottom of the bore hole and having no physical connections with the surface of the ground save the electrical conductors for energizing the pump and perhaps a lifting cable.

A more specific object of the present invention is to provide a pumping arrangement so compactly coordinated that a long lived pump may be encased in a supporting structure receivable within the limited confines of a well casing.

Other objects will become apparent to those skilled in the art when the following description is read in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic view showing the lower end of a deep well bore hole provided with a pump constructed in accordance with the present invention, it Ibeing understood that the illustration of Figure 1 is limited to that portion of the bore hole which is adjacent the producing formation;

Figure 2 is a view corresponding to Figure 1, but showing the operative parts of the pumping arrangement in the opposite position to that illustrated in Figure 1;

Figure 3 is a longitudinal sectional view of a practical embodiment of the upper portion of the pumping arrangement constructed in accordance with the present invention;

Figure 4 is a sectional view taken along line of Figure 3; and

Figure 5 is a longitudinal sectional view of th lower extremity of the embodiment, the upper extremity of which is shown in Figure 3, it being understood that Figure 5 is a continuation of Figure 3.

According to the present invention, an oil well or other comparable small bore deep well is pumped by an unitary electric motor and pump assembly which is lowered into the bore hole to near the producing formation, with electrical conductors, for supplying the motor, extending to the surface of the ground and energized by a suitable source. The invention contemplates that the producing formation be packed oi with a suitable packer having a tube extending into the producing formation and that the pump assembly be in sealing engagement with the packer and tube so as to draw fluid vfrom the producing formation through the tube without allowing fluid to pass by the packer in a downward direction.

In order that the pumping assembly be sunlciently compact that it can be emplaced in the well :bore hole with clearance for up-owing oil and without necessitating the running of tube lines from the bottom of the hole to the surface of the ground, the invention contemplates that a pair of oppositely acting pumps be arranged onev above the other within a body whose overall diameter is suiciently less than that of the casing of the well that ample clearance exists therebetween. In order to actuate the Dumps without moving parts which would be difllcult to accommodate within the limited connes of the bore hole, a fluid driving system, containing a fixed volume of working iiuld such as clean lubricating oil, is provided. The working iuid system isycompletely closed so that the working uid is maintained entirely separate from, and never commlngles with, the crude oil being pumped.

Consequently, all moving mechanical parts of the pumping apparatus are relieved of the deleterious 'action of sand, water, or other foreign matter with which the crude oil from the producing formation may be contaminated.

In such a fluid-driven pump system, the working fluid is forced out of the working side of one pump into the working side of the other and vice versa to move a movable wall of the respective pumps and thus expand and contract the working fluid sides of both pumps reciprocally. Concurrently with expansion of the working fluid side of a pump, the crude oil (or other pumping fiuid) side of that pump is contracted and vice versa. Valves are, of course, provided to admit crude oil to the crude oil side of a pump'as the working uid side of that pump is contracting, and other valves release the crude from the pump as the working iiuid side thereof expands.y

In view of the impossibility of reversing the rotation of an electric motor without switches and.

3 the desirability of eliminating the necessity for numerous conductors extending from the bottom of the well to the surface of the ground Where such switches might be operated feasibly, this invention contemplates that the electric motor near .the bottom of the well be rotated always in the same direction. Consequently, the impeller driven by the motor operates always in the same direction. To accomplishreversal of the direction of iiow of working fluid between the respective pumps, valves are provided. A special feature of the invention is the control of such valves automatically by the dierential between the hydrostatic head of crude oil on the apparatus and the fluid pressure within the working fluid system, pressure 'being allowed to`build up on the working fluid in one pump until such pressure substantially exceeds (by for example p. s. i.) the hydrostatic head of crude on the apparatus; thereupon the valves operate to reverse the flow of working uid between the pumps until the working uid in the opposite pump is under suiiicient pressure (in excess of the hydrostatic head) to actuate the valves back to their original position. The cycle is then repeated.

In the embodiments to be described hereinafter, the movable walls which separate the working fluid side of each pump from the pumping fluid side thereof are in the form of expansible and contractible sleeves, but it will be understood that, so long as the wall is movable and yet capable of maintaining the integrity of the working fluid, any suitable wall may be utilized, such as a bellows, diaphragm, or piston,

Referring now to Figure 1 of the drawings for a diagrammatic illustration of the invention,` a pump embodying the present invention is emplaced in the bore hole I of an oil well provided .with a casing 2 extending down to near the producing formation 3. Seated upon the bottom of the bore hole I is a. tube. I perforated to admit oil from the formation to the interior thereof. The tube 4 is provided with a ball valve 5 resting upon a. seat 6 and adapted to close upon the application of pressures from` above. About the exterior of the tube l is a packer 1 of any suitable well known variety adapted to seat against the interior of casing 2 and effect a seal therewith. As shown in the drawings, the upper end of packer 'I is coned to receive the coned nose 8 of the pump assembly. The nose 8 of the pump assembly is also provided with a protuberance 9 adapted to pass through the packer I and approach ball 5 in such spaced relation that the latter has sufcient room to operate.

The pump assembly involves a cylindrical member Il) provided with a plurality of chambers. ducts, and valves so interconnected as to constitute a. working system separate and apart from a pumping system. 'While in the diagrammatic illustration of Figures 1 and 2, the cylindrical member I0, which constitutes the housing of the entire pump assembly, is shown as one piece, it will be understood that for convenience in manufacturing it is preferred to fabricate the housing of a plurality of different pieces assembled togather to constitute a composite cylindrical structure, as illustrated, for example, more in detail in Figure 3. The entire organization is. energized by means of an axially elongated electric motor II, which is relatively small in its radial dimension, so as to fit Within the casing of an oil well and yet leave sufficient clearance about its periphery to permit the passage of oil upwardly through the casing. A cable I2 4 extends from the motor II to the surface oi' the ground where it is suitably connected to a source of electromotive power. The lower extremity of shaft I2 of motor I| is provided with an impeller I3, so as to be driven by the motor, such, for example, as in the direction indicated by the arrow thereon. vThe impeller I3 is located in a chamber I4, which is provided with an outlet duct I5 and an inlet duct I6, it being understood that, in the embodiment illustrated, it is contemplated that the impeller I3 be rotated always in the same direction.

The outlet duct I5, after being deviated to bypass a diaphragm-valve assembly I1, extends to a port I8 leading into a valve chamber I9. The valve chamber |9 is provided with a plunger 20 having three heads 2|, 22, and 23, each in sealing engagement with the interior wall of chamber I9.

Similarly, the inlet duct I6 extends into communication with valve chamber I9 at port 24 and, after being deviated to by-pass a4 duct 25 leading from a port 26 in chamberv I9, extends therebeyond to another port 2l into chamber I9. The chamber I9 is provided with a. further port 28 leading to a duct 29, which, after being deviated to by-pass a diaphragm-valve assembly 30, extends to the interior of a pump chamber 3|. The pump chamber 3| is provided with an elastic sleeve 32 having its ends sealed against the end walls of chamber 3|, but having its interior in communication with duct 29. The space within sleeve 32 is closed, save for the duct 29, and constitutes a space for the reception of working uuid. The sleeve 32 may be constructed of any suitable resilient material` which is resistant to oil, that is to say, will survive a great multiplicity of expansions and contractions while immersed in mineral oil. Any of a considerable variety of synthetic rubbers are suitable materialsfor the construction of sleeve 32, as, for example, a Buna N synthetic rubber known as Hycar." Other such synthetic rubbers, such as butadiene or neoprene, may be utilized with equal advantage.

The exterior periphery of sleeve 32 is spaced from the interior periphery of chamber 3l, so

as to denne an annular space therebetween constituting the crude oil or pumping fluid side of the pump. From the lower end of said space there extends a duct 33, controlled by a ball valve 35 adapted to close the port into duct 33 when pressure is applied Within chamber 3|. Duct 33 extends to the lower end of the pump assembly and communicates directly with the interior of protuberance 9 adjacent ball valve 5.

The duct 25, which, as mentioned hereinbefore, originates at port 26 of valve chamber |9, extends downwardly through the cylindrical body I0, deviating to by-pass the pump chamber 3| and nally terminates in a pump chamber` 35. Pump chamber 35 is identical with pump chamber 3|, previously described, being likewise provided with an elastic sleeve 36 and having a ball valve 3l' controlling the port to the duct 38, which latter extends to the lower end of pump asl sembly and connects with the interior of proto be opened upon the application of pressuresA within vpump chamber 3|. Similarly, pump chamber 35 is provided with a ball valve 4I controlling a port leading into exit passage 42.

Diaphragm-valve I1 is provided with an exterior flexible member 43 having its outer surface arranged to be in contact with, and consequently* subject to the hydrostatic head of, the crude oil surrounding the exterior of the pump assembly. Extending .from the diaphragm 43 is a stem 44 provided with a pair of tappets 45 and 46 arranged, respectively, to seal against seats 41 and 48, the former being closed and the latter being open when the hydrostatic pressure on the exterior of diaphragm 43 exceeds the hydrostatic pressure on the interior thereof. A duct 49 extends from duct 29, previously described, to the interior of diaphragm 43. From the chamber between seats 41v and 48, a duct 50 extends to the upper end of valve chamber I9. From the chamber adjacent tappet 46, a port 5| communicates with duct I6. Consequently, when the hydrostatic head acting on the exterior of diaphragm '43 is sufficiently in excess of the fluid pressure on the inside of the diaphragm, the valve I1 is actuated to the position shown in Figure 1,

Whereat tappet 45 is closed upon Seat 41, but a passageway is open, from duct I6 to the upper end of chamber I9, through port 5|, by tappet 46 and duct 5|). The position of the partsshown in Figure l is that which they occupy immedi-` ately after actuation of the diaphragm-valve I1, while the position of the parts shown in Figure 2 is the opposite position of the parts to be described more in detail hereinafter.

Diaphragm-valve 30 is identical with diaphragm-valve I1 and the same reference characters are applied to the respective parts thereof save the ducts and ports. A duct 52 extends from duct 25, previously described, to the interior oi diaphragm 43 of valve 36. A duct 53 extends from the lower end of valve chamber I9 to the chamber between the tappets of diaphragm-valve 30. A further duct 54 extends from duct I6 to the chamber-adjacent tappet 46 of valve 30. In this instance, when the pressure of the fluid in duct 25 is substantially in excess of the hydrostatic head acting on the exterior of diaphragmvalve 30, the parts will be in the position shown in Figure 1.

With the apparatus thus described in detail from the diagrammatic illustration of Figure 1,

it will be understood that, when the impeller I3 is being operated so as to force fluid out through duct |5, as indicated by the arrow therein, it will reach valve chamber I9 at port |8 and, with the plunger 20 in the position shown in Figure 1, will ilow out of valve chamber I9, through duct 29, to the interior of sleeve 32. Continued ow of the fluid in this direction will expand the ilexible sleeve 32 from its collapsed position, shown in full lines, to its expanded position, shown in dotted lines. During the expansion ofsleeve 32, as just described, such crude oil from the formation 3 as was present in pump chamber 3| outside of sleeve 32, when the cycle began, will be forced outwardly past valve 39.

To supply the working fluid for forced expansion of sleeve 32, as just described, working fluid is drawn by impeller I3 from within sleeve 36 of pump chamber 35, through duct 25, port 26, valve chamber I9 (between heads 2| and 22), port 24, and duct IB, as indicated by the arrows in Figure 1. After this operation has continued for a time suiiicient that enough working fluid has been withdrawn from pump chamber 35 to fully expand sleeve 32 -in pump chamber 3|, apressure will develop on that side of the working sys.. tem, between chamber 3| and impeller I3, in excess of the hydrostatic head of the fluid on the exterior of the pump assembly. Such pressure will be communicatedby duct 49 to theinterior of diaphragm" 43 of valve I1. When the pressure on the inside of rdiaphragm 43 of valve I1 sufllciently exceeds the surrounding hydrostatic head to actuate valve I1, the latter Will move in a di-f. rection such as to close the passageway at tapv pet 46 and'oper'i the passageway at tappet 45. Such actuation of the valve changes the communication of the upper end of valve chamber I9 from the negative side of the system to the positive side thereof and thus a force is applied to the upper end of head 2| tending to move plunger 20 downwardly. When such movement of the plunger 20 has been accomplished, the parts will have assumed the position shown in Figure 2, where port 24 will have been closed by head 2|, port I8 'will have been opened to port 26 and duct 25, and port 28 will be in communication -with port 21 and duct I6.

The parts having assumed the position illustrated in Figure 2, continued operation of the..

impeller I3, as previously, will force working iluid, as indicated by the arrows in Figure 2, from duct I5, through port I8, t0 port 26, through duct 25, to thev interior of sleeve 36 in pump chamber 35, expanding the sleeve from the full line position shown in Figure 2 to the dotted line position therein, and concurrently forcing such oil as was sucked through duct 38 into chamber 35 (by the collapsing of sleeve 36) during the previous phase of the operation, outwardly past valve 4|.

During the phase of the operations wherein the working iluld is being forced into pump chamber 35 to expand sleeve 36, as just described, workup in duct 25 and communicates through duct 52 to the interior of diaphragm 43 of valve 30. When such pressure has sufliciently exceeded the external hydrostatic pressure to actuate valve 33. duct 53 leading to the lower end of valve chamber I9 is thrown into communication with duet 5-2 and pressure from duct 25 is thence applied upon the lower end of head 23 of plunger 20 to actuate the latter upwardly, restoring the same to the position shown'in Figure l. The cycle of operations is then repeated.

Figure 3 of the drawings illustrates a practical embodiment of the present invention less, the motor Il, the iinpeller I3, packer 1, and tube 4, which is to say that the device shown in Figure 3 involves an assembled structure including a system of valves, ducts, and cylinders corresponding in principle to that hereinbefore described in connection with Figures 1 and 2, but showing an arrangement of parts which may be manu'iacarrangement are housed. The electric motor II, with its adjunct impeller I3, is adapted to be suitably connected to the upper end of member 0|.

In assembng the apparatus shown in Figure 3, a core piece |04, provided with a ball valve seat |05 arranged to accomodate the ball valve 3l, h'ereinbefore referred to, and having a duct |08, is seated upon the upper surface of nose member |03, so that the duct |08 and the chamber leading to seat |05 are in communication with a cen- |04 is circumferentially reduced, as shown at |01', in order to provide a communication with the chamber surrounding ball valve 31. 'I'he top surface of core piece |04 is shouldered to receive a rigid tube |08 and also flexible sleeve 36, the same being secured in hermetically sealed relation to the upper surface of core piece |04. The upper ends of sleeve 36 and tube |08 are likewise secured in hermetically sealed relation to a core piece |09, the exterior of which is reduced at its lower end, asshown at H0, in order to provide a channel of communication from the space within member |02 (but outside sleeve 38) to a valve seat ||I for the reception of ball valve 4|. Adjacent ball valve 4I, member |02 is provided with a window I|2, across which a suitable screen or guard member may be provided for preventing the escape of ball 4 i.

The core piece |09 is provided with two distinct ducts ||3 and ||4 extending in a. generally axial direction therethrough without intersecting the chamber surrounding ball valve 4|. Duct I I3 is connected to the hollow interior of tube |08, while duct ||4 extends into communication with the space between the exterior of tube |08 and the interior of sleeve 36, the lower end of duct H4 being annular, as shown at IIS. At the upper terminus of duct I3, core piece |08 is provided with a ball valve seat IIE for -the reception of ball valve 33.

outer periphery of the upper end of core piece I1 is reduced, as shown -at |20, to provides. communicating passageway from chamber H8 into the crude oil side of a pump chamber corresponding to chamber 3|, described in connection with Figure 1. Seated in hermetically sealed relation upon the upper end of core piece ||1 are parts |2| and 32, being duplicates, respectively, of parts |08 and 36, described above. The upper extremities of parts |2| and 32 are connected in hermetieally sealed relation to the lower end of a core axially extending ducts I 23 and |241, the lower end of the latter being annular, as shown at |25, and communicating with the space between sleeve 32 and tube |2|. Duct |23 connects with the interior of tube I2I. Core piece |22 is exteriorly reduced at its lower end, as shown at |26, to provide a channel of communication to the ball valve seat |27, upon which ball valve 39 operates. Adjacent ball valve 39, member |02 is provided with a window |28 having a screen or guard suitable for preventing the escape of ball 39.

In hermetically sealed engagement with the |29 is of less diameter at its lower end Athan the central bore of member |0I, so as to provide an annular channel about the exterior of tube |29 communicating with duct |24 in core piece |22.

e upper end of tube |29 communicates with a duct |30 in member I 0| Member |0| is provided with another duct ISI, which communicates with the annular channel surrounding tube |29. lmmediately above tube |29, the diaphragm-valve 30 is inserted in member |0| and above the latter a valve sleeve I 32 is inserted in the central bore of member I 0| for the reception of, and cooperation with, plunger 20. The sleeve |32, therefore, deines the valve chamber, designated as I9 in Figures l and 2. An auxiliary duct |33 extends upwardly from duct |3| parallel with the central Vbore in member |0| to a chamber I 34 for the reception of diaphragm-valve l.

Member |0| is also provided with ducts I5 and w shown in dotted lines as on the same side of'said Duct |0 has its port 24 opening in alignment with ports |35 of sleeve |32. Said duct I 6 has its lower port 21 opening in alignment with port |36 of sleeve |32. Duct I8 has its port I8 opening in alignment with port |31 of sleeve I 32.

stood that, when the same reference characters occur on Figures 1 and 3, identical parts are indicated. The inlet and outlet ducts I5 and I8. with their respective ports I8, 24, and 21, are indicated by the same reference characters on Figure 3. The duct 29 of Figure 1 has its counterpart in duct |3| of member |0I, the annular space surrounding tube |29, and duct |24 in core piece |22.

The duct 25, shown in Figure l, has its countertrally through the lower pump, while maintaining the integrity of the working fluid system in the latter. Conversely, working fluid for the lower pump chamber is supplied centrally through the upper pump chamber.

Referring now to Figure 4 of the drawings, y

the diaphragm-valves of the character utilized at and 30 are shown in detail and consist of a against the interior thereof is a follower |5|q Associated with foling ring |53, therefore, constitutes the counterpart of tappet 45, referred to in connection with Figures 1 and 2. At the opposite end of stem 44 is a head |56 having a packing ring |51 adapted to seat against a shoulder |58 of member I 55 and constituting the counterpart of tappet 46, described in connection with Figure 1. StemA 44 is provided with a central bore |59 having an orifice |60 communicating with the central chamber of member |55 and anotherorifice IBI communicating witha groove about follower |5|, so as to maintain a sealing film of oil. AAs previously indicated, ducts 52 effect. communication between duct |30 and the space surrounding shoulder |52, so that, as the pressure in duct |30 increases, follower |5| will be forced in a downward direction to bulge diaphragm 43 outwardly,

as shown. I

From the foregoing description, those skilled in the art should understand the construction, operation, the principle of the pumping arrangement of the present invention and realize that it provides an efficient mode of pumping deep wells without necessitating the running of tube lines or mechanical connections from the bottom of the well to the surface of the ground, and further "ber for pumping fluid, a 'chamber' for 'working fluid, and a movable wall separating the 'pumpthat kit provides an apparatus which may be safe- 1y and convenienty located thousands of feet below the surface of the ground without requiring frequent removal for replacement and repair of moving parts because, as hereinbefore indicated, the only mechanical moving parts of the apparatus are confined within the working fluid system, which is totally closed, and, assuming that the working iluid is free of contaminant when the apparatus is lowered into the well, no wear by abrasion or corrosion will be encountered.

While the invention has been disclosed with reference to diagrammatic showings, as well as a complete practical embodiment, it is realized that those skilled in the art will envision divers modiilcations and variations of the specic arrangement of parts which has been described without departing from the spirit of the invention. It is, therefore, to be distinctly understood that the invention is not limited to the specific arrangement of parts described.

Having thus described the invention, what is Patent is:

1. A deep well pump comprising an axially elongated body having a diameter less/than the bore hole of the well, a pair of oppositely acting pumps arranged in axially displaced relation in said body; each of said pumps having'a chamber for pumping fluid, a chamber for working fluid, and a movable wall separating the pumping fluid from the working fluid; fluid conduits interconnecting the working uid chambers of said pumps, said working fluid chambers and conduits constituting a closed system containing a fixed volume of working fluid; powered means located in one of said conduits for forcing circulation of working fluid through said conduits; and valves controlling the flow of pumping fluid.

2. A deep well pump comprising an axially elongated body having a diameter less than the bore hole of the well, a pair of oppositely acting pumps arranged in axially displaced relation in said body; each ofsaid'pumps having a chamber for pumping fluid, a chamber for working flu-id, and a movable wall separating the pumping fluid from the working fluid; fiuidconduits interconnecting the working fluid chambers of said pumps, said working fluid chambers and con- .claimed and desired to be secured by Letters lo, I

duits constituting. a closed systerncontainings.

ilxed volume ofworking fluid; valves controlling y the flow of pumping fluid, means in said body for circulating uid in said system, andmeans i for reversing `the direction of` flow of working` fluidA in and out of vsaid working iluidchambers.

3.` A deep well pump comprising an axially elongated body having a diameter less than thev bore hole of the well, 'a pair "of oppositelyacting pumpsarranged inaxially displaced relation* in saidbody; each of said pumps'havinga cham'- conduits constituting a closed system containing a fixed volume of working fluid; valves controlling y the ilow of pumping fluid, means in said bodyy for circulating fluid in said system, and means responsive to the hydrostatic head of fluid without the body for reversing the direction of flow ofY working fluid in and out of said workingv fluid chambers.A u

4. A deep well pump comprising an axially elongated body having a diameter less than the bore hole of the well, a pair of oppositely acting pumps arranged in axially displaced relation in said body; each of said pumps having a chamber for pumping fluid, a chamber for work'- ing fluid, and a collapsible4 and expansible tubular Wall separating the pumping fluid from the working fluid; iluidconduits interconnecting the working fluid chambers of said pumps powered means located in one of said conduits for forcing circulation of working fluid through said'conduits, said working fluid chambers and conduits constituting a closed system containing a fixed volume of working fluid; and valves controlling the flow of pumping fluid. y d i 5. Apparatus for pumping oil wells comprising a packer sealing the interior of the well `above the producing formation, a tube extending through the packer into the producing formation, a pair of oppositelyacting pumps located adjacentk said packer; each of saidpumps having a. crude oil supply conduit communicating with said tube and a crude Aoilr discharge opening above the packen. each of said Vpumps having a movable imperforate wall one side of which in fluid communication with the supply conduit and discharge opening therefor, andthe other vsideV through the packer into the producing iorma`r tion, a pair of oppositely acting pumps arranged one above the other adjacent said packer, working fluid circulatingmeans arranged adjagent perforate resilient tubular wall separating the same into a crude oil side and a working fluid side; ducts interconnecting the working vfluid sides of said pumps vand extending to saidcirculating means, the working fluid duct to ther lowerm'ost -pump extending axially throughthetubular wall of the uppermost pump. i

7. Apparatus forpumping oil wells comprising a packer sealing the interior of the well above the. producing formation, a tube extending and means adjacent said pumps fory through the packer into the producing formation, a pair of oppositely acting pumps arranged one above the other adjacent said packer', working uid circulating means arranged adjacent said pumps; each of said pumps having an imperforate resilient tubular wall separating the same into a crude oil side and a working iluid side; ducts connecting the crude oil side of the respective pumps with said tube; the crude oil duct for the uppermost pump extending axially through the tubular wall of the lowermost pump.

8. A pump of the character described for operation near the bottom of a column of fluid comprising, a cylindrical barrel having an electric motor at the upper end thereof arranged for rotation about an axis extending longitudinally of the barrel, an impeller dn'ven by said motor, a

' pair of pumps having movable walls, ducts interconnecting one side of the movable wall in each oi' said pumps with said vimpeller to constitute a completely closed working fluid system, and valves controlling the direction of fluid flow in said system, so that when one pump is being charged with working uid the other pump is being discharged.

9. A pump of the character described for operation near the bottom of a column of uid comprising, a cylindrical barrel having an electric motor at the upper end thereof arranged for rotation about an axis extending longitudinally of the barrel, an impeiler driven by said motor, a pairof pumps having movable walls, ducts interconnectingto said pumps and impeller to constitute a completely closed working uid system, valves controlling the direction of duid ow in said system sothat when one pump is being charged with working fluid the other pump is belngdischarged, said valves including a valve responsive to the differential between the hydrostatic head of said column of fluid and the working system pressure upon a pump to reverse the direction oivfluid now in said system.

. 10. A pump oi the character described for operation near the bottom of a column of fluid comprising. a cylindrical barrel having an electric motor at the upper end thereof arranged for rotation about an axis extending longitudinally of the barrel, an impeller driven bytsaid motor, a

pair of pumps having movable walls. ducts interconnecting to said pumps and impeller to constitute a completely closed working uid system,

valves controlling the direction of fluid flow in said system so that when one pump is being charged with working fluid the other pump is being discharged, said valves including a slide valve having-one end selectively connectable to receive the Working system pressure in one pump, the other end of said slide valve being selectively connectable to receive the working system pressure in the other pump, and means responsive to predetermined working system pressure within said pumps respectively to selectively connect an end of said slide valve to receive such pressure.

12 l1. A pump of the character described for op eration near the bottom of a column of iluid comprising, a cylindrical barrel having an electric motor at the upper end thereof arranged for rotation about an axis extending longitudinally of the barrel, an impeller driven by said motor, a pair of pumps having movable walls, ducts interconnecting to said pumps and impeller to constitute a completely closed working fluid system, valves controlling the direction of fluid flow in said system so that when one pump is being charged with working fluid the other pump is being discharged, said valves including a slide valve having one end selectively connectable to receive the working system pressure in one pump, the other end of said slide valve being selectively connectable to receive the working system pressure in the other pump, and means responsive to substantial excess of working system pressure on one pump above the hydrostatic head of the column of iluid to selectively connect an end of said slide valve to receive such pressure.

12. A pump of the character described for operation near the "bottom of a column of fluid comprising, a cylindrical barrel having an elecreceive the working system pressure in one pump.-

the other end of said slide valve being selectively y connectable to receive the working system pressure in the other pump, means responsive to excess of Working system pressure on one pump to selectively connect one end of said slide valve to such pressure, and means responsive to excess of working system pressure on the other pump to selectively connect the opposite end of said slide valve to such pressure.

ALBERT CARL v MCGOVNEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,852,242 Holt Apr. 5, 1932 1,967,746 Dulaney July 2 4, 1934 2,183,560 Gurley et al Dec. 19, 1939 2,260,306 Ferguson Oct. 28, 1941 2,269,789 Schmidt Jan. 13, 1942 2,291,912 Myers Aug. 4, 1942 2,404,524 Norton ,July 23, 1946 

